Apparatus and Method for Inflation Extrusion Molding of Pressure-Sensitive Adhesive Sheet

ABSTRACT

The present invention provides an apparatus for inflation extrusion molding of pressure-sensitive adhesive sheet, including: one or a plurality of extruders; a die into which one or a plurality of resin materials are respectively introduced and which extrudes from an ejection opening the resin materials into an inflated cylindrical shape having a predetermined diameter in accordance with an inflation method; and two stabilizers facing each other at a predetermined angle so as to upwardly approach each other, and defining a space therebetween through which the cylindrically-shaped resin materials extruded from the die are passed to be deformed into a pressure-sensitive adhesive sheet in a flattened elliptical shape having a predetermined width, in which the stabilizers each have a plurality of air floating portions each of which blows air toward the resin materials; and the stabilizers rotate in one direction around the central axis of the cylindrically-shaped resin materials.

This a divisional of application Ser. No. 12/832,381 filed Jul. 8, 2010,which claims priority from JP 2010-073371 filed Mar. 26, 2010 and JP2010-139486 filed Jun. 18, 2010; the entire disclosures of the priorapplications are considered part of the disclosure of the accompanyingdivisional application and is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an apparatus and method for inflationextrusion molding of a pressure-sensitive adhesive sheet. The presentinvention particularly relates to stabilizers that face each other at apredetermined angle, which are used for deforming a resin material(adhesive material) into a flattened elliptical shape after the resinmaterial is extruded from a die by means of inflation and inflated intoa cylindrical shape having a predetermined diameter; as well as to therotation of the stabilizers.

BACKGROUND OF THE INVENTION

As a manufacturing of a sheet in accordance with the inflation extrusionmolding technique, there has been a technique using guide rollers. Thistechnique includes transferring a cylindrically inflated sheet extrudedfrom an extruder while flattening the same by means of stabilizersincluding a plurality of rows of guide rollers. Since the techniqueenables efficient manufacture of sheets, the technique has hitherto,widely been utilized.

However, unlike manufacture of an ordinary sheet, in case where apressure-sensitive adhesive sheet having a pressure-sensitive adhesivelayer on one side thereof is manufactured by the inflation extrusionmolding method, when an attempt is made to convey a cylindrically-shapedpressure-sensitive adhesive sheet in the middle of inflating into acylindrical shape while flattening the same with a plurality of rows ofguide rollers, a mismatch often arises between a traveling direction ofthe cylindrically-shaped pressure-sensitive adhesive sheet and arotating-direction of the guide rollers. It is difficult for thecylindrically-shaped pressure-sensitive adhesive sheet to correct themismatch by sliding over surfaces of the guide rollers. Consequently, asurface of the pressure-sensitive adhesive tape thus obtained sometimesbecomes wavy or wrinkled.

Accordingly, another technique has been developed as an advanced versionof the above-mentioned technique. This technique makes it possible toprevent winkles, and the like, which would otherwise arise when a resinmaterial, such as a pressure-sensitive adhesive sheet, extruded inaccordance with the inflation technique is flatly folded (seeJP-A-2005-111980).

According to this technique, each of the stabilizers is built from aplurality of rows of rollers in which a plurality of rollers arearranged in a row, and directions of the respective rollers of thestabilizer are aligned to a substantially same direction where a resinmaterial spreads when deformed into a flattened elliptical shape.

It thereby becomes possible to readily deform a resin material of apressure-sensitive adhesive sheet extruded in accordance with theinflation method into a flattened elliptical shape and significantlyprevent winkles, and the like, which would otherwise arise after thepressure-sensitive adhesive sheet is folded.

This technique has made it possible to significantly prevent occurrenceof winkles, and the like, which would otherwise be caused after thesheet has been folded, as compared with the above-mentioned technique.As mentioned above, even when a slight difference exists between thetraveling direction of the sheet and the rotating-direction of therollers, in case of a pressure-sensitive adhesive sheet exhibiting smallpressure-sensitive adhesive force, it slides over the rollers, whereby aslight correction is made to the difference so that the sheet can run inits original traveling direction. Thus, the drawback has been resolved.

When an adherend is flat, there arises no problems with this technique.However, when the adherend has a rough surface, or the like, therearises a necessity for enhancing adhesiveness of the pressure-sensitiveadhesive sheet. When a pressure-sensitive adhesive exhibiting enhancedadhesiveness is made on the outermost surface of the sheet, thepressure-sensitive adhesive makes the sheet difficult to slide over therollers, so that the direction of the sheet cannot be corrected.Therefore, the sheet becomes more difficult to run in the original sheettraveling direction, and occurrence of wrinkles is found here and therein the resultant sheet.

SUMMARY OF THE INVENTION

The present invention has been conceived to solve the drawbacks of thesheet using a pressure-sensitive adhesive having such high adhesivenessand aims at providing an inflation extrusion molding apparatus andmethod that make it possible to easily deform even acylindrically-shaped pressure-sensitive adhesive sheet, which has beenextruded in accordance with an inflation method and which uses apressure-sensitive adhesive having such high adhesiveness, into aflattened elliptical shape and that also make it possible tosignificantly prevent occurrence of wrinkles, and the like, afterfolding of the sheet.

In order to accomplish the above-mentioned object, the present inventionprovides an apparatus for inflation extrusion molding ofpressure-sensitive adhesive sheet, the apparatus comprising:

one or a plurality of extruders;

a die into which one or a plurality of resin materials including atleast a resin material for forming a pressure-sensitive adhesive layerand extruded respectively from the extruders are respectively introducedand which extrudes from an ejection opening the resin materials into aninflated cylindrical shape having a predetermined diameter in accordancewith an inflation method; and

two stabilizers facing each other at a predetermined angle so as toupwardly approach each other, and defining a space therebetween throughwhich the cylindrically-shaped resin materials extruded from the die arepassed to be deformed into a pressure-sensitive adhesive sheet in aflattened elliptical shape having a predetermined width,

wherein the stabilizers each have a plurality of air floating portionseach of which blows air toward the resin materials; and

wherein the stabilizers rotate in one direction around the central axisof the cylindrically-shaped resin materials.

In an embodiment, the air floating portions each have an indentationformed at a surface of the stabilizer and an air outlet provided inproximity to a center of the indentation.

In another embodiment, the stabilizers each comprise a porous membercovering the surface thereof at which the air floating portions areprovided.

Furthermore, the present invention provides a method for inflationextrusion molding of pressure-sensitive adhesive sheet, the methodcomprising:

extruding one or a plurality of resin materials including at least aresin material for forming a pressure-sensitive adhesive layerrespectively from one or a plurality of extruders to respectivelyintroduce the resin materials into a die,

extruding the resin materials from the die into an inflated cylindricalshape having a predetermined diameter in accordance with an inflationmethod, and

passing the cylindrically-shaped resin materials through a space betweentwo stabilizers facing each other at a predetermined angle so as toupwardly approach each other, thereby preparing a pressure-sensitiveadhesive sheet in a flattened elliptical shape having a predeterminedwidth,

wherein air is blown from the stabilizers toward the resin materialswhen the resin materials are passed through the space between thestabilizers, and

wherein the stabilizers are rotated in one direction around the centeraxis of the cylindrically-shaped resin materials while the resinmaterials are passed through the space between the stabilizers.

In an embodiment, the pressure-sensitive adhesive sheet having passedthrough the space between the stabilizers is separated with a cutterinto two pieces.

Moreover, the present invention provides a pressure-sensitive adhesivesheet obtained through the above-mentioned method.

The configurations of the present invention yield the followingadvantages.

(1) Respective areas of the inflated cylindrical body including one or aplurality of resin material layers (resin material(s) in a form ofinflated cylindrical shape) slightly differ from each other in terms ofdirections of passage thereof. However, the present invention uses thestabilizers that blow (spray) air toward the resin material(s), wherebythe resin material(s) is/are floated by air so as not to be in contactwith the stabilizers. Accordingly, the respective areas of the resinmaterial(s) can move in their directions of passage, so that it becomeseasy to fold the sheet into a flattened elliptical shape withoutinvolvement of occurrence of wrinkles, and the like, at the surface ofthe obtained sheet.

(2) Moreover, since the resin material(s) is/are floated by air so asnot to be in contact with the stabilizers, the pressure-sensitiveadhesive layer does not adhere to the surfaces of the stabilizers.Hitherto-performed periodic maintenance, such as cleaning of thesurfaces of the stabilizers, becomes obviated.

(3) Rollers of conventional stabilizers encounter a problem ofextraneous matters (floating dust, or the like) attached to the rollersof the stabilizers adhering to an adhesive surface of a product, to thusdeteriorate product quality. On the contrary, in the present invention,the resin material(s) is/are floated by air so as not to be in contactwith the stabilizers. Therefore, the extraneous matters attached to thestabilizers do not adhere to the adhesive surface of the product. Hence,deterioration of product quality can be prevented.

(4) Because of nonuniform rotation of the rollers of conventionalstabilizers, the rollers raise a problem of scratches arising in thesurface of the product, thereby deteriorating product quality. However,in the present invention, the resin material(s) is/are floated by air soas not to be in contact with the stabilizers, and scratches, which wouldotherwise be caused by nonuniform rotation, can never arise, so thatdeterioration of product quality can be prevented.

(5) Moreover, for reasons of flow deviations (attributable to the shapeof the die, a temperature distribution of the die, and the like) ofresin material(s) coming out of the die, a change arises in thethickness of the pressure-sensitive adhesive sheet, so that the sheetcomes to exhibit a thickness distribution. In relation to a conventionalroll manufactured by winding, as is, the sheet exhibiting the thicknessdistribution, a specific area on the roll in its widthwise direction isstored, for a long period of time, while remaining irregular and bulgedfrom the other area. As a result, the sheet itself retains irregularity.When the sheet is withdrawn from the roll on occasion of use, theirregularity appears in the sheet. Therefore, when the sheet is affixedto an adherend, the irregular portion of the sheet is left as a wrinkle.On the contrary, in the present invention, the stabilizers are rotated;hence, even when the sheet is rolled up, the thickness distribution canbe let spread in the widthwise direction of the roll. Therefore, whenthe sheet is rolled up, the diameter of the roll can be made uniform,and the irregularity is not retained in a specific area. Consequently,even when the sheet is withdrawn from the roll on occasion of use, theirregularity is not left in the sheet. Therefore, no wrinkles appearwhen the sheet is affixed to an adherend.

(6) Furthermore, in an embodiment in which the stabilizers each includea porous member covering the surface thereof at which the air floatingportions are provided, since the intensity of air blown out of the airfloating portions is once suppressed by the porous member, the air blowsout more uniformly, so that uniform air layer can be formed on thesurface of the resin material(s).

Further, in an embodiment, the pressure-sensitive adhesive sheet havinga predetermined width having passed through a space between the twostabilizers is separated into two pieces with a cutter. Accordingly, asheet can be doubly produced by single inflation operation.

Moreover, in the present invention, since the resin material(s) is/arefloated so as not to be in contact with the stabilizers, thepressure-sensitive adhesive sheet do not adhere to the stabilizers, sothat wrinkles do not arise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an entire inflation extrusion moldingapparatus of the present invention.

FIG. 2 is a longitudinal cross-sectional view of a die shown in FIG. 1.

FIGS. 3A to 3D are four drawings for describing stabilizers according toembodiment 1 shown in FIG. 1, wherein FIG. 3A is a front view, FIG. 3Bis a side view, FIG. 3C is a top view, and FIG. 3D is a cross sectionalview that is taken along line D-D shown in FIG. 3A while viewed inarrowy directions.

FIGS. 4A and 4B are conceptual renderings for describing a direction ofconveyance of a sheet floated by air blown from the stabilizers, whereinFIG. 4A is a front view of a cylindrically-shaped sheet located in thevicinity of the stabilizer and FIG. 4B is a partially enlarged view.

FIG. 5 is a schematic diagram showing that a one-way rotary device isupwardly separated from the inflation extrusion molding apparatus shownin FIG. 1;

FIGS. 6A and 6B are conceptual renderings for describing the directionof conveyance of the sheet floated by the air blown from the stabilizerswhen the stabilizes are rotated, wherein FIG. 6A is a lateral crosssectional view of the stabilizer and FIG. 6B is a front view.

FIGS. 7A to 7D are four drawings for describing stabilizers according toembodiment 2 shown in FIG. 1, wherein FIG. 7A is a front view, FIG. 7Bis a side view, FIG. 7C is a top view, and FIG. 7D is a cross sectionalview that is taken along line D-D shown in FIG. 7A while viewed inarrowy directions.

FIGS. 8-1A, 8-1B and 8-2 are views for describing a sheet which isejected from a die that causes an area having a different thickness fromothers and is deformed into a flattened elliptical shape in accordancewith a conventional molding apparatus, wherein FIGS. 8-1A and 8-1B areplan views of a sheet deformed into a flattened elliptical shape, inwhich FIG. 8-1A is a plan view of one side of the sheet and FIG. 8-1B isa plan view of the other side, and FIG. 8-2 is a front view of a take-uproll achieved when the sheet shown in FIGS. 8-1A and 8-1B is rolled up.

FIGS. 9-1A, 9-1B and 9-2 are views for describing a sheet which isejected from a die that causes areas having a different thickness thanothers and is deformed into a flattened elliptical shape when anapparatus described in connection with JP-UM-B-7-30347 reciprocallyrotates stabilizers through 270°, wherein FIGS. 9-1A and 9-1B are planviews of a sheet resulting from deformation into the flattenedelliptical shape, in which FIG. 9-1A is a plan view of one side of thesheet, while FIG. 9-1B is a plan view of the other side of the same, andFIG. 9-2 is a front view of a roll into which the sheet shown in FIGS.9-1A and 9-1B is rolled up.

FIGS. 10-1A, 10-1B and 10-2 are views for describing a sheet which isejected from a die that causes areas having a different thickness thanothers and is deformed into a flattened elliptical shape when anapparatus described in connection with JP-UM-B-7-30347 reciprocallyrotates stabilizers through 360°, wherein FIGS. 10-1A and 10-1B are planviews of a sheet resulting from deformation into the flattenedelliptical shape, in which FIG. 10-1A is a plan view of one side of thesheet, while FIG. 10-1B is a plan view of the other side of the same,and FIG. 10-2 is a front view of a roll into which the sheet shown inFIGS. 10-1A and 10-1B is rolled up.

FIG. 11-1 A is a plan view of one of sheets produced by an apparatusaccording to the present invention, in which a sheet extruded from a diewhich causes areas having a different thickness than others is deformedinto a flattened elliptical shape and the sheet in a flattenedelliptical shape is then lengthwise cut with a cutter into two sheets,and FIG. 11-1B is a plan view of the other one of the sheets and FIGS.11-2A and 11-2B are front views of rolls into which the sheets shown inFIGS. 11-1A and 11-1B are rolled up.

DESCRIPTION OF REFERENCE NUMERALS AND SIGNS

10: resin material (pressure-sensitive adhesive sheet)

10A: sheet area close to stabilizer

10K: resin material for forming substrate layer

10N: resin material for forming pressure-sensitive adhesive layer

10H: resin material for forming back surface layer

20A: air floating portion

20B: air outlet

20K: indentation

20P: air pipe

100: cylindrical resin material generation device

110: extruder

110H: resin material feed port

120: die (dice)

120F: ejection opening

130: guide

200: one-way rotary device

200A: stabilizer according to embodiment 1

210A: stabilizer according to embodiment 2

200D: one-way rotor

200P: pinch roller

200R: guide roller

300: inflation extrusion molding apparatus

DETAILED DESCRIPTION OF THE INVENTION

An exemplary embodiment of an inflation extrusion molding apparatus ofthe present invention is now described by reference to the drawings.

Herein, according to the present invention, the term “sheet” refers tonot only a thin article having a predetermined thickness (e.g. 200 μm)or more, but also a thin article whose thickness is less than thepredetermined thickness, which is so called “film”.

FIG. 1 is a schematic diagram of an entire inflation extrusion moldingapparatus of an embodiment of the present invention, and a descriptionis provided by reference to an exemplary embodiment of manufacture of athree-layered pressure-sensitive adhesive sheet.

<Extruder 110>

In FIG. 1, a resin material 10K for forming substrate layer extruded byan extruder 110 from a resin material feed port 110H containing theresin material 10K in a melt state is introduced into a die (dice) 120.Likewise, a resin material 10N for forming pressure-sensitive adhesivelayer extruded by the extruder 110 from the resin material feed port110H containing the resin material 10N is introduced into the die 120.Similarly, a resin material 10H for forming back surface layer extrudedby the extruder 110 from the resin material feed port 110H containingthe resin material 10H is introduced into the die 120.

<Die 120>

FIG. 2 is a cross-sectional view showing flow channels of respectiveresin materials in the die 120. Resin materials (resin material 10H forforming back surface layer, resin material 10K for forming substratelayer, and resin material 10N for forming pressure-sensitive adhesivelayer) passed through the flow channels in communication with anejection opening 120F are concentrically and cylindrically extrudedupwardly from the annular and concentrically-made ejection opening. Anair inlet pipe (omitted from the drawings) is made in the die 120. Airis blown to the inside of the cylindrically-shaped resin materials 10H,10K, and 10N by way of the air inlet pipe, thereby inflating the resinmaterials 10H, 10K, and 10N from thick cylindrical shape having apredetermined diameter to thin cylindrical shape having a large diameter. In FIG. 2, the materials exit the annular upper ejection opening suchthat the resin material 10N for forming pressure-sensitive adhesivelayer comes into an external layer; that the resin material 10K forforming substrate layer comes into an internal layer; and that the resinmaterial 10H for forming back surface layer comes into a back surfacelayer. The layers approach each other as they ascend in the die 120, tothus be extruded from the ejection opening 120F of the die 120. Sinceair is blown to the inside of the thus-extruded sheet 10, the layers areextruded in the form of a thin cylindrical body inflated to apredetermined diameter in a mutually closely-bonded state.

<Cylindrically-Shaped Resin Materials 10 (Cylindrical Body IncludingResin Material Layers)>

In the case of the embodiment for making cylindrically-shaped resinmaterials (cylindrical body) 10, the respective resin materials areintroduced into corresponding flow channels in such a way that the resinmaterial 10N for forming pressure-sensitive adhesive layer comes intothe external layer; that the resin material 10K for forming substratelayer that is to serve as a substrate comes into the internal layer; andthat the resin material 10H for forming back surface layer comes intothe back layer. The respective resins approach each other as they ascendin the die 120. When extruded out of the ejection opening of the die120, the three layers of resin materials come into a large-diametercylindrically inflated sheet such that the layers of resin materialsremain in a close contact with each other, in sequence from inside tooutside, the resin material 10H for forming back surface layer, theresin material 10K for forming substrate layer, and the resin material10N for forming pressure-sensitive adhesive layer. In this embodiment, apressure-sensitive adhesive having especially high adhesiveness is used.The materials will be described in detail later.

<Guide 130>

The cylindrically-extruded resin materials 10 (10H, 10K, and 10N) ispositionally guided by a guide 130 so as not to move on all sides,whereupon the cylindrically inflated resin materials upwardly runwithout involvement of occurrence of movements.

<Stabilizer 200A>

The cylindrically inflated resin materials 10 are introduced into aspace between stabilizers 200A and 200A that face each other at apredetermined angle. After squeezed into a flattened elliptical shape,the resin materials 10 are guided into a space between a pair of pinchrollers 200P and 200P while being folded.

<Angle of Aperture Between the Stabilizers>

The two stabilizers 200A and 200A are arranged so as to face each otherat a predetermined angle (an angle of aperture) θ (see FIG. 4A) so as tonip the flow channel of the resin materials 10 with respect to thetraveling direction of the resin materials 10 so that the cylindricallyinflated resin materials 10 extruded from the die 120 can be deformedinto a flattened elliptical shape.

The angle of aperture θ between the stabilizers 200A and 200A must takeinto account a gradient of deformation of the cylindrically inflatedresin materials 10 achieved between the stabilizers 200A and 200A, andthe like. It is desirable to select the angle of aperture, asappropriate, according to the viscosity of the resin materials 10. Theangle of aperture is preferably set so as to fall within a range from10° to 45°, preferably from 10° to 30°, and more preferably from 10° to25°.

Embodiment 1 of the Stabilizer 200A Having Air Floating Portions>

As shown in FIGS. 3A to 3D, each of the stabilizers 200A and 200A is arectangular plate and has, on a surface thereof, a plurality of airfloating portions 20A, whereby the sheet can pass through a spacebetween the stabilizers 200A and 200A without contacting the stabilizers200A and 200A.

Configuration of the Air Floating Portions 20A>

Each of the air floating potions 20A has a rectangular indentation 20Kand an air outlet 20B provided in the vicinity of the center of theindentation 20K, both of which are provided on a surface of each of thestabilizers 200A. The air outlets 20B are connected to an air pipe 20P.Air to be blown (sprayed) from the air outlets 20B is fed from an airsupply source (omitted from the drawings) on the stationary side to theair pipe 20P on the rotary device side by way of a rotary joint (omittedfrom the drawings), to thus reach the air outlets 20B by way of the airpipe 20P. Since the rectangular indentations 20K are formed in a surfaceof each of the stabilizers 200A, the air blown from the air outlets 20Bspreads over interiors of the respective indentations 20K. The air thusspread over the interiors of the respective indentations 20K act ascontact pressure, to thus float (levitate) the sheet (resin materials).Hence, as will be described below, the entire sheet can be floated evenwhen the air outlets 20B are not so great in numbers.

<Layout of the Air Floating Portions 20A>

The plurality of air floating portions 20A are provided on each of thestabilizers 200A in both its lateral and longitudinal directions. InFIGS. 3A to 3D, three air floating portions are provided in the lateraldirection, and four are provided in the longitudinal direction. Thus, atotal of 12 air floating portions are provided in close contact witheach other without involvement of clearance. Air from the interiors ofthe indentations 20K acts as contact pressure, to thus float the sheet.Accordingly, even when the number of the air outlets 20B is small, theycan float the sheet from the stabilizers 200A in a non-contactingmanner. Therefore, the pressure-sensitive adhesive layer does notcontact the stabilizers 200A, and no wrinkles, and the like, arise onthe surface of the sheet. Thus, folding the sheet into a flattenedelliptical shape becomes facilitated.

<Function of the Stabilizers>

FIGS. 4A and 4B are conceptual renderings for describing a direction ofconveyance of a sheet passing between the stabilizers, wherein FIG. 4Ais a front view of a cylindrically-shaped sheet located in the vicinityof the stabilizer and FIG. 4B is a partially enlarged view fordescribing the direction of conveyance of the sheet by the air floatingportions 20A.

In FIG. 4A, the two stabilizers 200A are arranged, while orientedupwardly, so as to approach each other at the angle of aperture θ. Whentaken up by pinch rollers 200P positioned above the respective twostabilizers 200A, the cylindrically inflated resin materials 10gradually become deformed from the cylindrical shape into a flattenedelliptical shape while passing through the space between the twostabilizers 200A.

As shown in FIG. 4B, immediately-above-oriented drawing force acts on acertain area 10A of the sheet, and force for causing deformation of acylindrical shape into a flattened elliptical shape also acts on thecertain area 10A in a horizontal direction at a point between thestabilizers 200A. Consequently, the area 10A comes to move in adirection of a bubble movement resultant vector that is a combination ofa drawing-direction (immediately-above-oriented) vector and aspreading-direction (the horizontal direction) vector. As mentionedpreviously, since the air floating portions 20A float the sheet by meansof the air originated from the entire surfaces of the air floatingportions, the sheet can readily be floated in a non-contacting mannerfrom the stabilizers 200A even when the number of the air outlets 20B issmall. Therefore, respective areas of the sheet can readily move in thedirection of the bubble movement resultant vector. Since the vector ofthe traveling direction of the sheet coincides with the direction of thebubble movement resultant vector, the sheet areas 10A do not undergotorsion. Moreover, since the sheet is floated in a non-contactingmanner, the sheet does not contact the air flowing portions 20A.Therefore, the sheet is liable to neither scratches nor generation ofwrinkles.

Furthermore, since the sheet is floated by air in a non-contactingmanner, the pressure-sensitive adhesive layer does not come to adhere tothe surfaces of the stabilizers, so that hitherto practiced periodicmaintenance, such as cleaning of the surfaces of the stabilizers,becomes obviated.

<Processing 1 for the Sheet Passed Through the Pinch Rollers 200P>

Turning back to FIG. 1, a cutter (omitted from the drawings) is placedat a location where both ends of the resin materials 10 folded into aflat shape after having passed between the pinch rollers 200P and 200Pare to lie. The flatly folded resin materials 10 are cut into two rightand left pieces with the cutter as shown in FIG. 1. The thus-cut piecesare wound by take-up rollers (omitted from the drawings) situated atrespective ends by way of respective right and left guide rollers 200Rand 200R.

As mentioned above, in this embodiment, both ends of the thus-foldedresin materials are cut by means of the cutters, whereby a sheet can bedoubly manufactured by single inflation as compared with theconventional technique. Thus, productivity is considerably enhanced.

<Rotating the Stabilizers in One Direction>

The inflation extrusion molding apparatus shown in FIG. 1 includes astationary unit and a rotary unit. FIG. 5 is a schematic diagram showingthat a rotary device is separated upwardly with a view toward making thestationary unit and the rotary unit of the inflation extrusion moldingapparatus shown in FIG. 1 easy to understand.

In FIG. 5, reference numeral 100 designates a cylindrical resin materialproduction device (the stationary unit), and 200 designates a one-wayrotary device (the rotary unit). The one-way rotary device 200 includesthe two stabilizers 200A and 200A fastened on a one-way rotator 200D.When the one-way rotator 200D is slowly rotated in one direction bymeans of a motor (omitted from the drawings), the two stabilizers 200Aand 200A and take-up units (the guide rollers 200R) slowly rotate in onedirection, either.

<An Advantage of One-Way Rotation>

The resin materials 10 ascent from the cylindrical resin materialproduction device 100 enters a space between the stabilizers 200A and200A from an opening 200H formed in the center of the one-way rotator200D, thereby undergoing flattening. Simultaneously, the one-way rotor200D rotates around the resin materials 10, so that the stabilizers 200Aand 200A also rotate. Consequently, both folded ends of the resinmaterials 10 are formed at a location close to the viewer and anotherlocation distal from the viewer on a drawing sheet of FIG. 1. When theone-way rotor 200D rotates in a direction of an arrow through 90°, bothends of the resin material 10 are formed at right and left sides on thedrawing sheet. When the one-way rotor 200D rotates in the direction ofthe arrow through 90° in this state, respective ends of the resinmaterial 10 are formed at the location close to the viewer and thelocation distal from the viewer. When the one-way rotor 200D furtherrotates in the direction of the arrow through 90°, both ends of theresin material 10 are formed at right and left sides on the drawingsheet. When the one-way rotor 200D additionally rotates in this state inthe direction of the arrow through 90°, the resin material returns tothe state shown in FIG. 1. Thus, both folded ends move over the entireperimeter of the cylindrically-shaped resin materials. Consequently, thethickness of the cylindrically-shaped resin materials becomes uniformover the entire perimeter, and a protuberance does not arise when thesheet is taken up.

FIGS. 6A and 6B are conceptual renderings for describing the directionof conveyance of the sheet floated by the air blown from the stabilizerswhen the stabilizes are rotated, wherein FIG. 6A is a lateral crosssectional view of the stabilizer and FIG. 6B is a front view. As shownin FIG. 6A, when the stabilizers 200A rotate in a direction of an arrow,a sheet area 10A close to the stabilizers also comes to undergo theforce in the rotating-direction (the horizontal direction).

Consequently, the bubble movement resultant vector exerted on the sheetarea 10A is equal to a result of “rotating-direction vector” beingfurther added to the resultant vector shown in FIG. 4B. Therefore, thebubble movement resultant vector greatly differs from thedrawing-direction vector.

However, the traveling direction of the sheet is free by virtue offloating effected by the air floating portions 20A adopted by thepresent invention. Consequently, if the direction of the bubble movementresultant vector has greatly changed from the drawing-direction vector,the sheet will move in the direction of the bubble movement resultantvector. Therefore, even when the stabilizers 200A are rotated, a problemof occurrence of wrinkles, and the like, does not arise.

Embodiment 2 of the Stabilizer 200A Having Air Floating Portions>

In this embodiment, as shown in FIGS. 7A to 7D, each of the stabilizers200A and 200A is a rectangular plate and has, on a surface thereof, aplurality of air floating portions 20A. Each of the air floating potions20A has a rectangular indentation 20K and an air outlet 20B provided inthe vicinity of the center of the indentation 20K, both of which areprovided on a surface of each of the stabilizers 200A. The air outlets20B are connected to an air pipe 20P. In this embodiment, a porousmember 21 covers the surface of each stabilizer 210A at which the airfloating portions are provided

Owing to this constitution, the intensity of air blown out of airoutlets 20B of the air floating portions 20A is once suppressed by theporous member 21, and then the air blows out through porous paths insidethe porous member 21. Therefore, the air blows out more uniformly incomparison with embodiment 1, so that uniform air layer can be formed onthe surface of the resin materials (sheet).

Although the material of the porous member 21 is not limited, metalmaterials such as stainless steel, titanium, copper, nickel, aluminumand alloys thereof; sintered body (ceramics) such as alumina (Al₂O₃) andsilicone carbide (SiC); glass fibers; and polymer materials such aspolyethylene (PE), polypropylene (PP), ethylene/vinyl acetate copolymer(EVA), polyacetylene (PA), poly(methyl methacylate) (PMMA),acrylonitrile/styrene copolymer (AS), acrylonitrile/butadiene/styrenecopolymer (ABS), polycarbonate (PC), polyvinyl chloride (PVC),poly(vinylidene fluoride) (PVDF) and polytetrafluoroethylene (PTFE).

The pore size of the porous member 21 is preferably 0.1 to 1,000 μm,more preferably 1 to 500 μm, and furthermore preferably 10 to 50 μm.

The porosity of the porous member 21 is preferably 10 to 80%, morepreferably 10 to 50%.

The thickness of the porous member 21 is preferably 5 to 30 mm, morepreferably 5 to 20 mm, and furthermore preferably 8 to 15 mm.

FIGS. 8-1A, 8-1B and 8-2 are views for describing a sheet which isejected from a die that causes an area having a different thickness fromothers (the area is herein tentatively taken as “protuberance R”) and isdeformed into a flattened elliptical shape in accordance with aconventional molding apparatus. FIGS. 8-1A and 8-1B are plan views of asheet deformed into a flattened elliptical shape, wherein FIG. 8-1A is aplan view of one side of the sheet and FIG. 8-1B is a plan view of theother side. FIG. 8-2 is a front view of a take-up roll achieved when thesheet shown in FIGS. 8-1A and 8-1B is rolled up.

When a change exists in the viscosity of the cylindrically-shaped sheetin its circumferential direction due to temperature distribution at theejection opening of the die or when the pressure-sensitive adhesive isejected in a disproportionate quantity, a change arises in the thicknessof the sheet, whereupon an area which has a different thickness thanothers occasionally arises (the area is taken as protuberance R in FIGS.8-1A and 8-2). In this case, when the stabilizers 200A are left fastenedas conventionally, the area having a different thickness than others isformed along a lengthwise direction of the sheet and in parallel with anedge of the same, only at a point corresponding to an angle α° in thewidthwise direction of the sheet as shown in FIG. 7-1A. Therefore, whensuch a sheet is rolled up as shown in FIG. 8-2, a protuberance bulgingin a circumferential direction arises in a location on the surface ofthe cylindrical roller corresponding to the angle α°.

When the sheet is stored in a rolled state along with such aprotuberance, an unevenness caused by the protuberance is retained inthe sheet itself. Therefore, when the sheet is withdrawn from the rollduring use and affixed to an adherend, the unevenness left in the sheetitself is also left, as it is, in the form of a wrinkle on the adherend.

Meanwhile, since the apparatus described in connection withJP-UM-B-7-30347 reciprocally rotates the stabilizers through 180° to360°, the protuberance R having a different thickness spreads in itslateral direction, to thus become uniform. For this reason, theprotuberance that is shown in FIG. 8-2 and generated by the conventionalapparatus is prevented. However, the apparatus described in connectionwith JP-UM-B-7-30347 also encounters occurrence of a radial difference.FIGS. 9-1A, 9-1B and 9-2 are views for describing a sheet which isejected from the die that causes areas having a different thickness thanothers and is deformed into a flattened elliptical shape when anapparatus described in connection with JP-UM-B-7-30347 reciprocallyrotates stabilizers through 270°, wherein FIGS. 9-1A and 9-1B are planviews of a sheet resulting from deformation into the flattenedelliptical shape, in which FIG. 9-1A is a plan view of one side of thesheet, while FIG. 9-1B is a plan view of the other side of the same, andFIG. 9-2 is a front view of a roll into which the sheet shown in FIGS.9-1A and 9-1B is rolled up.

In FIGS. 9-1A, 9-1B and 9-2, the stabilizers are rotated through 270°.Therefore, during the course of rotation of the stabilizers, theprotuberances R, which are the only areas having a different thicknessin the widthwise direction such as those shown in FIGS. 9-1A and 9-1B,obliquely proceed with respect to the edge of the sheet as the sheetruns in its lengthwise direction. Consequently, the protuberances Rspread in their widthwise direction in this zone. Hence, when the sheetis rolled up, the roll is made uniform as indicated by reference symbolK shown in FIG. 9-2 in the zone from α° to 270°+α, so that theprotuberance (shown in FIG. 8-2) disappears.

Incidentally, when the point corresponding to 270°+α is achieved, thestabilizers make a U-turn. Therefore, when the sheet is rolled up, theprotuberances R do not spread in their widthwise direction in a zonefrom 270°+α to 0°+α. Therefore, an area that is smaller than the uniformarea K in terms of the diameter of the roll arises as in the area Hshown in FIG. 9-2. Consequently, a radial difference (K−H) arises at twolocations in a boundary between the area H and the area K.

Moreover, in the case of reciprocal rotation, rotation of thestabilizers is stopped at the time of a U-turn, whilst inflation is notstopped. Therefore, the protuberances R at each of turning points α° and270°+α° stay for a period of ti that is longer than a period duringwhich the protuberance R stays in the other area. Thus, there are formedprotuberances in which only portions corresponding to the turning pointsare greater in their lengthwise direction. The protuberances are alwaysformed at the same points in their widthwise direction. Accordingly,when the sheet is rolled up, the protuberances T generated as a resultof the stabilizers continuously staying for the period tl finally appearin two points (steps) as shown in FIG. 9-2.

When the sheet including the radial difference and the protuberances Tis stored in a rolled state, an unevenness caused by the radialdifference and the protuberances is retained in the sheet itself.Therefore, when the sheet is withdrawn from the roll during use andaffixed to an adherend, the unevenness left in the sheet itself is alsoleft, as it is, in the form of a wrinkle on the adherend.

FIGS. 10-1A, 10-1B and 10-2 are views for describing a sheet which isejected from the die that causes areas having a different thickness thanothers and is deformed into a flattened elliptical shape when anapparatus described in connection with JP-UM-B-7-30347 reciprocallyrotates stabilizers through 360°, wherein FIGS. 10-1A and 10-1B are planviews of a sheet resulting from deformation into the flattenedelliptical shape, in which FIG. 10-1A is a plan view of one side of thesheet, while FIG. 10-1B is a plan view of the other side of the same,and FIG. 10-2 is a front view of a roll into which the sheet shown inFIGS. 10-1A and 10-1B is rolled up.

In FIGS. 10-1A, 10-1B and 10-2, the stabilizers are caused to make aU-turn at an angle of 360°, whereupon the protuberances R spread intheir widthwise direction, to thus become uniform as indicated byreference symbol K shown in FIG. 10-2. For this reason, the radialdifference (K−H), such as that shown in FIG. 9-2, is resolved.

However, as described in connection with FIG. 9-2, rotation of thestabilizers is stopped at the time of a U-turn, whilst inflation is notstopped. Therefore, when the protuberances R at the turning point a stayfor a period t1 that is longer than the period during which theprotuberances R stay in the other area. Thus, there are formedprotuberances T in which only portions corresponding to the turningpoint are greater in their lengthwise direction.

When the sheet including the protuberances T is stored in a rolledstate, an unevenness caused by the protuberances is retained in thesheet itself. Therefore, when the sheet is withdrawn from the rollduring use and affixed to an adherend, the unevenness left in the sheetitself is also left, as it is, in the form of a wrinkle on the adherend.

On the contrary, according to the present invention, the stabilizers200A are continually rotated in one direction. Accordingly, as shown inFIGS. 11-1A and 11-1B, the protuberances R having a different thicknessthan others continually proceed (without involvement of a U-turn) intheir widthwise direction. Therefore, even when both ends of the sheetin a flattened elliptical shape (flattened elliptical body) are cut witha cutter so as to be separated into two sheets and then thethus-separated two sheets are respectively rolled up, the protuberancesR having a different thickness spread in their widthwise direction, tothus become uniform like K as shown in FIGS. 11-2A and 11-2B. For thesereasons, the protuberances (shown in FIG. 8-2), the radial difference(K−H shown in FIG. 9-2), and the protuberances T (shown in FIGS. 9-2 and10-2) do not generate.

Consequently, even when the sheet is withdrawn from the roll during useand affixed to an adherend, no wrinkles arise on the adherend becausethe sheet itself does not include any unevenness.

<Moldable Resin Material>

As mentioned above, the resin material 10 easily spreads between thestabilizers 200A and 200A, and irregular occurrence of wrinkles isprevented. Therefore, various types of resin materials can be molded.Examples of moldable resin materials include homopolypropylene; block,random or other propylene polymers containing ethylene units ascomonomer units; ethylene polymers such as low-density ethylenepolymers, high-density ethylene polymers, and linear low-densityethylene polymers; polystyrene; polyesters; olefin polymers that arecopolymers of ethylene and other monomer(s) such as ethylene/methylmethacrylate copolymers; styrene/isoprene/styrene block copolymers(SIS); styrene/butadiene/styrene block copolymers (SBS);styrene/isoprene block copolymers (SI); styrene/butadiene blockcopolymers (SB); styrene/ethylene-propylene/styrene block copolymers(SEPS); styrene/ethylene-butylene/styrene block copolymers (SEBS);styrene/ethylene-butylene-propylene block copolymers (SEP);styrene/ethylene-butylene block copolymers (SEB);styrene/ethylene-butylene/olefin crystal block copolymers (SEBC); olefincrystal/ethylene-butylene/olefin crystal block copolymers (CEBC);styrene/isobutylene/styrene block copolymers (SIBS); styrene/butadienerandom copolymers (SBR); hydrogenated styrene/butadiene randomcopolymers (HSBR); ethylene/vinyl acetate copolymers (EVA);ethylene/propylene rubbers (EPR); and ethylene/propylene/a-olefinrubbers. These resin materials may be used solely or as a mixture of twoor more of them.

<Resin Material for Forming Pressure-Sensitive Adhesive Layer>

As mentioned above, molding of various resin materials is possible. Forinstance, even when a pressure-sensitive adhesive layer is provided onone side of a sheet such as a pressure-sensitive adhesive sheet, apressure-sensitive adhesive sheet free from occurrence of wrinkles canbe produced.

Examples of the resin materials for forming pressure-sensitive adhesivelayer include styrene/isoprene/styrene block copolymers (SIS);styrene/butadiene/styrene block copolymers (SBS); styrene/isoprene blockcopolymers (SI); styrene/butadiene block copolymers (SB);styrene/ethylene-propylene/styrene block copolymers (SEPS);styrene/ethylene-butylene/styrene block copolymers (SEBS);styrene/ethylene-butylene-propylene block copolymers (SEP);styrene/ethylene-butylene block copolymers (SEB);styrene/ethylene-butylene/olefin crystal block copolymers (SEBC); olefincrystal/ethylene-butylene/olefin crystal block copolymers (CEBC);styrene/isobutylene/styrene block copolymers (SIBS); styrene/butadienerandom copolymers (SBR); hydrogenated styrene/butadiene randomcopolymers (HSBR); ethylene/vinyl acetate copolymers (EVA);ethylene/propylene rubbers (EPR); and ethylene/propylene/α-olefinrubbers. The resin materials may be used solely or as a mixture of twoor more of them.

In addition, examples of the resin materials for formingpressure-sensitive adhesive layer include SEEPS[styrene/(ethylene-ethylene/propylene)/styrene block copolymers].

Moreover, resin materials that can be used for forming substrate layer,such as thermoplastic urethane and acryl block copolymers which will bedescribed later may be employed as a resin material for formingpressure-sensitive adhesive.

As an acrylic block copolymers for forming pressure-sensitive adhesive,acrylic block copolymers (A) composed of methacrylic copolymer blocks(a) containing ester of methacrylic acid as a principal component andacrylic copolymer blocks (b) containing ester of acrylic acid as aprincipal component may be mentioned. A structure of the acrylic blockcopolymers (A) may be either linear block copolymers or branched (star)block copolymers or a mixture thereof. Such a structure of the blockcopolymers is selected, as appropriate, according to physical propertiesof the required acrylic block copolymers (A). The linear blockcopolymers are preferable in view of cost and ease of polymerization.

The linear block copolymers may assume either of the structures.However, provided that the methacrylic copolymer blocks (a) are taken as“a” and that the acrylic copolymer blocks (b) are taken as “b” from theviewpoint of physical properties of the linear block copolymer andphysical properties of compositions, it is preferable that the linearblock copolymers be composed of at least one type of acrylic blockcopolymers selected from the group consisting of (a-b)n-type acrylicblock copolymers, b-(a-b)n-type acrylic block copolymers, and(a-b)n-a-type acrylic block copolymers (“n” is an integer of more thanone; for instance, an integer from one to three). Among these acrylicblock copolymers, a-b-type di-block copolymers, a-b-a-type tri-blockcopolymers, or a mixture thereof are preferable in view of ease ofhandling during processing or physical properties of compositions.

The resin material for forming pressure-sensitive adhesive layer mayalso contain other components, as required. Examples of other componentsinclude olefm resins; silicone resins, liquid acrylic copolymers;polyethylene imines; fatty amides; phosphate esters; and commonadditives. Types, number, and quantity of other components to becontained in the resin material for forming pressure-sensitive adhesivelayer can be appropriately set according to an objective. Examples ofthe additives include tackifiers; softeners; antioxidants; hinderedamine light stabilizers; ultraviolet absorbers; and fillers or pigments,such as calcium oxide, magnesium oxide, silica or zinc oxide, andtitanium oxide.

<Tackifiers>

In order to further improve adhesiveness, tackifier (tackifier resin)may be added to the resin material for forming pressure-sensitiveadhesive layer. Examples of the tackifiers include petroleum resins ofan aliphatic type, an aromatic type, an aliphatic/aromatic copolymertype, or an alicyclic type; coumarone-indene resins; terpene resins;terpene-phenol resins; alkylphenol resins; rosin resins; polymerizedrosin resins; xylene resins; and resins obtained by hydrogenating theseresins. One or more appropriate materials selected from these tackifierscan be used.

<Softeners>

Likewise, examples of the softeners include low-molecularpolyiosbutylene; polybutene; polyisoprene; polybutadiene; hydrogenatedpolyisoprene; hydrogenated polybutadiene; derivatives thereof that havea reactive group such as an OH group, a COOH group, or an epoxy group atone end or both ends thereof; process oils; naphthenic oil; castor oil;linseed oil; soybean oil; phthalic ester plasticizers, phosphoric esterplasticizers; and liquid aliphatic petroleum resins. One or moreappropriate materials selected from these tackifiers can be used.

<Resin Material for Forming Substrate Layer>

Examples of resin material for forming substrate layer includehomopolypropylene; block, random or other propylene polymers containingethylene units as comonomer units; ethylene polymers such as low-densityethylene polymers, high-density ethylene polymers, and linearlow-density ethylene polymers; polystyrene; polyesters; olefin polymersthat are copolymers of ethylene and other monomer(s) such asethylene/methyl methacrylate copolymers; styrene/isoprene/styrene blockcopolymers (SIS); styrene/butadiene/styrene block copolymers (SBS);styrene/isoprene block copolymers (SI); styrene/butadiene blockcopolymers (SB); styrene/ethylene-propylene/styrene block copolymers(SEPS); styrene/ethylene-butylene/styrene block copolymers (SEBS);styrene/ethylene-butylene-propylene block copolymers (SEP);styrene/ethylene-butylene block copolymers (SEB);styrene/ethylene-butylene/olefin crystal block copolymers (SEBC); olefmcrystal/ethylene-butylene/olefin crystal block copolymers (CEBC);styrene/isobutylene/styrene block copolymers (SIBS); styrene/butadienerandom copolymers (SBR); hydrogenated styrene/butadiene randomcopolymers (HSBR); ethylene/vinyl acetate copolymers (EVA);ethylene/propylene rubbers (EPR); and ethylene/propylene/α-olefinrubbers. In addition, examples of the resin materials for formingsubstrate layer further include thermoplastic polyesters (that can beused alone), homopolypropylene (random polypropylenes and blockpolypropylenes may also be used), and ethylene/vinyl alcohol copolymer(EVOH). The aforementioned thermoplastic urethanes and the acrylic blockcopolymers may also be used as the resin material for forming substratelayer. These resin materials may be used solely or as a mixture of twoor more of them.

The resin material for forming substrate layer may contain anappropriate additive, if necessary.

In addition to those additives as mentioned above, examples of theadditives that can be contained in the resin material for formingsubstrate layer include ultraviolet absorbers, heat-resistantstabilizers, fillers and lubricants. Types, number, and quantity ofadditives to be contained in the resin material for forming substratelayer can be appropriately set according to an objective.

<Ultraviolet Absorbers>

Examples of the ultraviolet absorbers include benzotriazole compounds,benzophenone compounds and benzoate compounds. In relation to anultraviolet absorber content, an arbitrary, appropriate content can beadopted unless otherwise bleed out arises during formation of amultilayered film. Typically, 0.01 part by weight to 5 parts by weightof a ultraviolet absorber is contained with reference to 100 parts byweight of thermoplastic resin in the substrate layer.

<Heat-Resistant Stabilizers>

Examples of the heat-resistant stabilizers include hindered aminecompounds, phosphor compounds and cyanoacrylate compounds. In relationto a heat-resistance stabilizer content, an arbitrary, appropriatecontent can be adopted unless otherwise bleed out arises duringformation of a multilayered film. Typically, 0.01 part by weight to 5parts by weight of a heat-resistant stabilizer is contained withreference to 100 parts by weight of thermoplastic resin in the substratelayer.

<Fillers>

Examples of the fillers include inorganic fillers such as talc, titaniumoxide, calcium carbonate, clay, mica, barium sulfate, whisker andmagnesium hydrate. A preferable average particle size of the filler is0.1 μm to 10 μm. In relation to a filler content, 1 part by weight to200 parts by weight of a filler is preferably contained with referenceto 100 parts by weight of thermoplastic resin in the substrate layer.

In an embodiment, in the case of producing a pressure-sensitive adhesivesheet, at first, the resin material for forming pressure-sensitiveadhesive layer and the resin material for forming substrate layer arerespectively fed into a die 120 from respective separate extruders. Theresin material for forming pressure-sensitive adhesive layer and theresin material for forming substrate layer fed into the die 120 are thenextruded together through annular openings provided in the die 120 insuch a way that the resin material for forming pressure-sensitiveadhesive layer becomes an exterior layer. The reason why the resinmaterials are extruded in such a way that the resin material for formingpressure-sensitive adhesive layer becomes an exterior layer is toprevent interior surfaces of a resultant pressure-sensitive adhesivesheet from adhering to each other after the sheet has been foldedbetween the stabilizers 200A and 200A.

As mentioned above, the inflation extrusion molding apparatus ofpressure-sensitive adhesive sheet according to the present inventionmakes it possible to form various resin materials, includingpressure-sensitive adhesive sheets, with high quality and withoutinvolvement of occurrence of wrinkles.

EXAMPLES

The inflation extrusion molding apparatus of the present invention ishereunder described specifically by reference to examples in which apressure-sensitive adhesive sheet is taken by way of example. However,the inflation extrusion molding apparatus of the present invention isnot limited to the following examples.

Example 1

Block polypropylene (WINTEC WFX6 manufactured by Japan PolypropyleneCorporation) as a material for forming substrate layer was fed to aresin feed port 110H of a screw extruder 110 having a diameter of 60 mm.100 parts by weight of a resin mixture composed of 75 parts by weight ofstyrene/ethylene-butylene/styrene block copolymers (SEBS) (G1657manufactured by Kraton Polymers Ltd.) and 25 parts by weight oftackifier (ARKON P-125 manufactured by Arakawa Chemical Industries Ltd.)as a material for forming pressure-sensitive adhesive layer were fed toa resin feed port 110H of another screw extruder 110 having a diameterof 60 mm. The extruder for pressure-sensitive adhesive was operated at arevolution speed of 15 rpm, and the extruder for substrate was operatedat a revolution speed of 140 rpm, so that the resin materials werepoured into a die 120. The die 120 had a diameter of 400 mm, and theannular ejection opening was concentrically and doubly provided. A gapof each ejection opening was 3.0 mm. The respective resin materials weremolded through coextrusion while a preset temperature of the extruderfor pressure-sensitive adhesive was set to 220° C. on the average; apreset temperature of the extruder for substrate was set to 180° C. onthe average; and a preset temperature of the die 120 was set to 220° C.The resin material 10 that had been molded through coextrusion andinflated into a cylindrical shape passed through a space between thestabilizers 200A and 200A, to thus be molded so as to become folded in aflattened elliptical shape. Employed stabilizers 200A and 200A are thoseshown in FIGS. 3A to 3D; in other words, a total of 12 air floatingportions 20A; namely, three air floating portions 20A in the lateraldirection and four air floating portions 20A in the longitudinaldirection on each of the stabilizers.

As a result of the resin material having passed through the spacebetween the stabilizers, two pressure-sensitive adhesive sheets, each ofwhich measured 110 μm in thickness and 1350 mm in width, could beobtained. Surfaces of the respective sheets were free from wrinkles, andthe respective sheets had a substantially uniform thickness. Thus, highquality pressure-sensitive adhesive sheets were produced.

Comparative Example

The stabilizers using rollers, which are described in connection withJP-A-2005-111980, were employed in comparative example. Specifically,each of the stabilizers included a first roll unit and a second rollunit that were symmetrically arranged so as to assume an inclinationangle of 6° and that were also made of PTFE. In the first roll unit, 56narrow-width rollers, each of which had a width of 17 mm and a rolldiameter of 46 mm, were provided in a row, and the respective rollerswere attached at a pitch of 55 mm such that a gap between the rollerscame to 9 mm. The row was arranged in eight layers. In the second rollunit, 90 narrow-width rollers, each of which had a width of 12 mm and aroll diameter of 38 mm, were provided in a row, and the respectiverollers were attached at a pitch of 50 mm such that a gap between therollers came to 12 mm. The row was arranged in two layers. The firstroll unit and the second roll unit ware arranged such that a gaptherebetween came to 8 mm. The narrow-width rollers were arranged in azigzag layout, and an angle of aperture θ was set to 24°. The same resinmaterials as that described in connection with example 1 was moldedunder the same conditions except use of the stabilizers including thenarrow-width rollers arranged in a zigzag layout and an angle ofaperture θ set to 24°. Two pressure-sensitive adhesive sheets, each ofwhich measured 110 μm in thickness and 1350 mm in width could thereby beobtained.

However, surfaces of the respective sheets included irregular wrinkles.

As mentioned above, according to the present invention, there isobtained an inflation extrusion molding apparatus that easily foldsresin material(s) into a flattened elliptical shape without involvementof occurrence of wrinkles on a surface thereof and that makes itpossible to let areas of the resin material(s) having a differentthickness spread.

While the present invention has been described in detail and withreference to specific embodiments thereof, it will be apparent to oneskilled in the art that various changes and modifications can be madetherein without departing from the scope thereof.

This application is based on Japanese patent application No. 2010-073371filed Mar. 26, 2010, the entire contents thereof being herebyincorporated by reference.

1. An apparatus for inflation extrusion molding of pressure-sensitiveadhesive sheet, said apparatus comprising: one or a plurality ofextruders; a die into which one or a plurality of resin materialsincluding at least a resin material for forming a pressure-sensitiveadhesive layer and extruded respectively from the extruders arerespectively introduced and which extruders from an ejection opening theresin materials into an inflated cylindrical shape having apredetermined diameter in accordance with an inflation method; and twostabilizers facing each other at a predetermined angle so as to upwardlyapproach each other, and defining a space therebetween through whichsaid cylindrically-shaped resin materials extruded from the die arepassed to be deformed into a pressure-sensitive adhesive sheet in aflattened elliptical shape having a predetermined width, wherein thestabilizers each have a plurality of air floating portions each of whichblows air toward the resin materials; and wherein the stabilizers rotatein one direction around the central axis of said cylindrically-shapedresin materials.
 2. The apparatus according to claim 1, wherein the airfloating portions each have an indentation formed at a surface of thestabilizer and an air outlet provided in proximity to a center of theindentation.
 3. The apparatus according to claim 1, wherein thestabilizers each comprise a porous member covering the entire surfacethereof at which the air floating portions are provided.
 4. A method forinflation extrusion molding of pressure-sensitive adhesive sheet, saidmethod comprising: extruding resin materials respectively from aplurality of extruders to introduce the resin materials into a die,extruding the respective resin materials from the die into cylindricalbody inflated to have a predetermined diameter in accordance with aninflation method, and passing the cylindrical body through a spacebetween two stabilizers facing each other at a predetermined angle so asto upwardly approach each other, thereby preparing a pressure-sensitiveadhesive sheet having a predetermined width, wherein the stabilizers arerotated in one direction around the center axis of the cylindrical bodywhile the cylindrical body is passed through the space between thestabilizers, and wherein the stabilizers each have air floating portionseach having an indentation formed at a surface of the stabilizer and anair outlet provided in proximity to a center of the indentation areused, whereby the air blown from said air outlets spreads over interiorsof said indentation to act as a contact pressure to float the sheet. 5.The method according to claim 4, wherein the pressure-sensitive adhesivesheet having a predetermined width, which had passed through the spacebetween the stabilizers, is separated with a cutter into two pieces. 6.A pressure-sensitive adhesive sheet obtained through the methodaccording to claim 4.